Performing the function that damaged kidneys cannot do effectively, hemodialysis is a process whereby a machine intercepts blood flow, removes toxins and excess water, and returns the cleansed blood to the body in an uninterrupted continuous circulation. This is accomplished with the aid of two methods of blood retrieval and return (i.e., through a tube [a hemodialysis catheter implanted in and protruding out of the chest] or a “fistula” [an artery-vein connection within the arm]). The preparation of a patient for hemodialysis is a two-step process involving the following surgical procedures:                1. the insertion of the catheter into the upper chest cavity—half of its length inside the body and half of its length hanging loosely outside of the chest cavity—for the purpose of immediately beginning dialysis, and        2. the creation of the fistula by connecting an artery to a vein buried under the skin inside one arm.        
The fistula will ultimately become the permanent port for hemodialysis. However, it requires maturation time for the fistula to heal properly—anywhere from 3 to 6 months—in order to be usable. Therefore, the catheter is the initial means to begin hemodialysis up until the fistula under the skin is ready for use, at which time the catheter is removed.
The fistula under the skin is accessed by using two large hypodermic needles inserted at the beginning of each session and removed at the end of each session. The needle insertion points close over and heal between each treatment so there is no risk of infection from waterborne contaminants.
However, some people's skin and arm flesh react poorly to this method, and the catheter must be relied upon indefinitely.
Unlike the needle used with the fistula, the catheter remains permanently in place during its months or years of use, leaving a possible avenue for infection to enter the body. To minimize the risk of infection, the end of the catheter that protrudes from the body is lightly wrapped in fresh gauze by the nurse. Before each hemodialysis treatment, the wrap is taken off from around the catheter and at the end of the treatment a fresh gauze wrap is applied around the catheter. All this time, the catheter does not move from its implanted position. Since the gauze wrap is not waterproof, moisture and water coming in contact with any part of the catheter or its entry port into the body present a serious risk of infection. Consequently, the patient is cautioned to keep dry the catheter's components and entry port.
This restriction poses obvious problems with regard to bathing, showering, and swimming.
There are several types of waterproof hemodialysis catheter covers available to protect the catheter and its entry port from water infiltration, each with its own disadvantages.
Korshield is a reusable, soft plastic, rubber-collared one-piece cape that is pulled on and off over the head and used for showering only. The collar can come unglued or stretch, and there is some discomfort after showering because the cape is dripping wet and the material quickly gets cold. In addition, it is sold in three sizes so obtaining the correct size is essential in order for the product to be effective.
Cover Cath (for shower and bath only), Liquishield (for shower only), Shower C.A.P. (for shower only), and Shower Shield (for shower only) are one-time use, disposable products that employ a plastic bag configuration or plastic film sheet with an adhesive material around the underside perimeter that seals to the skin. Most appear to require considerable manipulation to apply and remove. Cath Dry (for shower, bath, and swimming) is also a one-time use, disposable product. In addition, the examples of these competing products, with the exception of Cover Cath, are shown using an unwrapped catheter. This suggests that the unskilled patient may be required to take extra, time-consuming steps to unwrap and re-wrap the catheter every time he/she wants to bathe.